As with many common verbs, the meaning of “to say” in the Bible is highly dependent on context. Who is speaking? Who is hearing? What is it about? Is it a command, a message, an apology, instruction? All these things enter into the meaning of “say.” In general, though, “saying” has to do with sharing truth at various levels -- from the most exalted power people can have to perceive the Lord's desires directly to the most basic of orders issued to people at their lowest.

7291. 'You shall say to Aaron' means influx and communication - of the law of God, represented by Moses, with the doctrinal teachings, represented by 'Aaron'. This is clear from the meaning of 'saying', when done by Moses to Aaron, as influx and communication, as in 6291. Here 'saying' is similar in meaning to 'speaking', namely both influx and communication, which is meant by 'speaking', see 7270. The only way that this influx and communication can be expressed in the historical narratives of the Word is by the words 'saying and 'speaking'. The reason why the law of God, represented by 'Moses', was to flow into the doctrinal teachings, represented by 'Aaron', is that the law of God is internal truth, while doctrinal teachings are external truth; and it is a general rule that internal things flow into external, not the other way round, for the reason that internal things are more refined than external, whereas external things are grosser, being generalized expressions of the internal ones.